`My genes made me do it' may be defense of future, geneticist warns

Growing evidence that a person's genes influence behavior may create serious dilemmas for law enforcement during the next few years, a noted geneticist said here.

People accused of murder, rape and other violent crimes may increasingly adopt a new defense strategy, which amounts to "my-genes-made-me-do-it," he said."Genes do appear to influence behavior," said Dr. Leroy Hood, chairman of the department of molecular biotechnology at the University of Washington in Seattle.

"Since our system of law is based on free will and individual responsibility, could a future criminal argue extenuating circumstances because his genes made him commit the criminal act?"

Dr. Hood cited a mounting body of scientific evidence that the genes a person inherits from parents affect behavior. He attended a genetics conference sponsored here by Johns Hopkins University and the Jackson Laboratory, a noted genetics research facility.

Genes seem to influence a wide variety of human behavior in addition to criminal behavior. Researchers, for instance, have found that genes inherited from parents may help to decide whether a person will be homosexual or heterosexual.

Researchers have identified genes that increase the chances of a person engaging in "thrill-seeking" behavior. Other studies have linked certain genes to a tendency toward neurotic behavior. Neurotics have unpleasant mental symptoms that include unusual levels of anxiety.

Dr. Hood cited a variety of evidence linking genes and violent criminal behavior.

He said that Dutch researchers identified a family in which eight males had engaged in rapes, brutal assaults and other violent crimes. All had defects in a gene related to a neurotransmitter. None of the other family members who underwent tests had the gene defect.

Researchers emphasize that simple inheritance of a behavior-related gene does not necessarily mean that a person will engage in that behavior. Some people may have "modifier" genes that mute or eliminate effects of the behavior-related gene. Factors in the environment, such as family experiences, also may influence whether a gene affects behavior.